CECXG (3'-ethyl-LY-341,495) is a research drug which acts as a potent and selective antagonist for the group II metabotropic glutamate receptors (mGluR2/3), with reasonable selectivity for mGluR3. While it is some five times less potent than LY-341,495 at mGluR3, it has 38x higher affinity for mGluR3 over mGluR2,[1] making it one of the few ligands available that is able to distinguish between these two closely related receptor subtypes.[2][3][4]